Light Emitting Device

ABSTRACT

Light emitting device  1  includes an LED chip  10 , a mounting substrate  20  carrying the LED chip, a dome-shaped color conversion member  70 , and encapsulation member  50 . Color conversion member  70  is molded from a transparent resin material and a fluorescent material which is excited by a light emitted from the LED chip to emit a light of a color different from a luminescent color of the LED chip, and is bonded to the mounting substrate to surround LED chip  10 . Encapsulation member  50  is made of an encapsulation resin material to encapsulate LED chip  10  and bonding wires  14  within a space confined between mounting board  20  and color conversion member  70 . Encapsulation member  50  is of a convex-shape to have its light output surface  50   b  kept in an intimate contact with an internal surface of color conversion member  70 . Since the intimate contact between the convex-lens shaped encapsulation member  50  and the color conversion member is made without the use of a conventional frame, the light emitting device can restrain the generation of voids in the encapsulation member, and therefore give improved reliability. Moreover, the light output efficiency is also improved.

TECHNICAL FIELD

The invention relates to a light emitting device using a LED (LightEmitting Diode) chip and a manufacturing method thereof.

BACKGROUND ART

Japanese Unexamined Patent Application Publication No. 2001-85748(hereinafter referred to as patent document 1) and Japanese UnexaminedPatent Application Publication No. 2001-148514 (hereinafter referred toas patent document 2) propose a light emitting device which comprises aLED chip, a circuit board mounting the LED chip, a metal frame (e.g.made of aluminum) surrounding the LED chip on a surface of the circuitboard, and an encapsulation member (e.g. made of an transparent resinsuch as an epoxy resin and a silicone resin) filled within the frame toencapsulate the LED chip and bonding wires connected to the LED chip.The frame disclosed in the Patent document 1 and 2 is shaped to have anopening area which becomes greater as it is spaced further away from thecircuit board and is finished to have a mirror interior face whichserves as a reflector reflecting a light emitted from the LED chip.

Further, the patent document 2 discloses the light emitting device whichutilizes a blue LED chip with blue luminescence to radiate a whiteluminescent spectrum by use of a yellowish fluorescent material which isdispersed in a transparent resin encapsulating the blue LED chip to beexcited by the light from the blue LED chip.

When an epoxy resin is used as a material of the encapsulation member inthe light emitting device, bonding wires may be cut off when subjectedto a heat cycle test (temperature cycle test) of repeating a lowtemperature period of −40° C. and a high temperature period of 80° C.alternately, due to thermal-expansion of an electrically conductivepattern mounted on a substrate of a circuit board in the hightemperature environment.

On the other hand, when a silicone resin is used as a material of theencapsulation member in the light emitting device, the bonding wires canbe prevented from being cut off in the high temperature period of theheat cycle test because of that the encapsulation member is gelatinousand elastic. However, since a linear expansion coefficient of thesilicone resin, which is a material of the encapsulation member, is morethan 10 times that of an aluminum which is a material of the frame,voids may be generated within the encapsulation member due to thedifference in linear expansion coefficient between silicone resin andaluminum.

Furthermore, in the light emitting device, although the light emittedfrom the LED chip can be taken to external of the encapsulation membereffectively by means of the frame finished with a mirror interior face,there is a failure of causing light loss resulting from the reflectionof the light on the interior face of the frame.

Besides, in the light emitting device according to the Patent document1, when a lens controlling an orientation of the light emitted from theLED chip is arranged over the encapsulation member and the frame, alight output may be lowered due to a deviation between an optical axisof the LED chip and that of the lens, resulting from dimensionalaccuracy or assembling accuracy of the frame and the lens.

The Patent document 2 also discloses a light emitting device in whichthe encapsulating member of the LED chip and the bonding wires connectedthereto are configured to have its portion shaped into a convex lens.However, since the light emitting device utilizes a fluorescent materialwhich is dispersed partially or entirely in the encapsulation member,its concentration is likely to vary from portions to portions in theencapsulation member, causing color ununiformity. Further, when thefluorescent material is dispersed entirely in the encapsulation member,an increased amount of the fluorescent material is necessary with anattendant cost increase. It is possible that a dome-shaped colorconversion member is molded from a fluorescent material and atransparent resin material and is arranged to form an air layer aroundthe encapsulation member. However, in this instance, the colorconversion member has to be relatively large in size, and requires anincreased amount of the fluorescent material. Further, the air layerbetween the conversion member and the encapsulation member may cause atotal reflection at the interface between the encapsulation member andthe air layer depending upon the shape of the encapsulation member,thereby reducing the light output.

DISCLOSURE OF THE INVENTION

In view of the above problem, the present invention has beenaccomplished and has an object of providing a light emitting device anda method of manufacturing the same capable of improving light output aswell as its reliability and being manufactured at a reduced cost.

The light emitting device of the present invention includes a lightemitting diode (LED) chip, a mounting substrate to which the LED chip ismounted, a dome-shaped color conversion member, and an encapsulationmember. The color conversion member is molded from a transparent resinmaterial and a fluorescent material which is excited by a light from theLED chip to emit a light of a color different from a luminescent colorof the LED chip and is secured on the mounting substrate so as tosurround the LED chip. The encapsulation member is made from anencapsulation resin material to encapsulate the LED chip within thespace confined between the mounting substrate and the color conversionmember. The feature of the invention resides in that the encapsulationmember is shaped to have a convex lens with its light output surfacewhich is held in intimate contact with an interior surface of the colorconversion member.

Since the light emitting device of the present invention is configuredto have the convex lens shaped encapsulation member which is held inintimate contact with the interior face of the color conversion memberwithout requiring a conventional frame, the encapsulation member can befree from generating voids therein during a low temperature range in theheat cycle test to improve reliability. Furthermore, non-use of theconventional frame surrounding the LED chip can improve a light outputof the device. Besides, the color conversion member can be reduced insize with an attendant cost reduction.

Preferably, the mounting substrate comprises a heat conductive platemade of a heat conductive material, and a dielectric substrate stackedon the heat conductive plate, the dielectric substrate being provided onits surface opposite to the heat conductive plate with a pair of leadpatterns for electrical connection respectively with electrodes of theLED chip. The dielectric substrate has a through-opening inside of whichthe LED chip is mounted to the heat conductive plate with a planarsub-mount member interposed therebetween. The sub-mount member has alarger size than the LED chip and thermally couples the LED chip to theheat conductive plate in order to relieve a stress applied to the LEDchip due to a difference in linear expansion coefficient between the LEDchip and the heat conductive plate.

In this case, the sub-mount member acts to efficiently radiate a heatgenerated in the LED chips through the heat conductive plate, andrelieve the stress applied to the LED chip due to the difference inlinear expansion-coefficient between the LED chip and the heatconductive plate.

Preferably, the sub-mount member is designed to have a thickness suchthat a surface of the LED chip facing the sub-mount member is spacedfrom the heat conductive plate by a distance greater than that betweenthe heat conductive plate and an edge of the color conversion memberopposed to the mounting substrate.

In this instance, the light emitted from the lateral side of the LEDchip can be prevented from leaking out through the juncture between thecolor conversion member and the mounting substrate.

Preferably, the color conversion member is shaped to have a sphericalinner surface about the LED chip for intimate contact with the lightoutput surface of the encapsulation member.

In this instance, the light emitted from the LED chip can advance thecolor conversion member only with a minimum variation in an optical pathfor restraining color ununiformity.

A method of manufacturing the light emitting device in accordance withthe present invention is preferred to include the followings steps.

-   (a) the step of mounting the LED chip to the mounting substrate to    couple the LED chip to the mounting substrate by means of bonding    wires;-   (b) the step of covering the LED chip and the bonding wires with an    uncured first encapsulation resin material which becomes one part of    the encapsulation member;-   (c) the step of poring an uncured second encapsulation resin    material, which is the same material as the first one and becomes    the other part of the encapsulation member, inside the color    conversion member, and positioning the color conversion member on    the mounting substrate; and-   (d) the step of curing each of the first and second encapsulation    resin materials to form the encapsulation member.

With this method, the encapsulation member can hardly suffer fromgeneration of voids in the manufacturing process.

Preferably, the color conversion member in the light emitting device ofthe present invention is formed with an injection port for pouring theencapsulation resin material into the space confined between the colorconversion member and the mounting substrate, and also with a dischargeport for discharging the excess of the encapsulation resin material.

Further, the method of manufacturing the light emitting device in thepresent invention may include the following steps.

-   (a) the step of mounting the LED chip to the mounting substrate to    couple the LED chip to the mounting substrate by means of the    bonding wires;-   (b) the step of fixing the color conversion member on the mounting    substrate carrying the LED chip thereto;-   (c) the step of filling an uncured encapsulation resin material    within the space confined between the color conversion member and    the mounting substrate through the injection port of the color    conversion member;-   (d) the step of curing the encapsulation resin material to form the    encapsulation member.

Also with this method, the encapsulation member can hardly suffer fromgeneration of the voids in the manufacturing process.

Besides, the method of manufacturing the light emitting device inaccordance with the present invention may include the following steps.

-   (a) the step of mounting the LED chip to the mounting substrate to    couple the LED chip to the mounting substrate by means of the    bonding wires;-   (b) the step of covering the LED chip and the bonding wire with the    uncured first encapsulation resin material which becomes one part of    the encapsulation member;-   (c) the step of fixing the color conversion member on the mounting    substrate after the step (b);-   (d) the step of filling the uncured second encapsulation resin    material, which is the same material as the first one and becomes    the other part of the encapsulation member, within the space    confined between the color conversion member and the mounting    substrate through the injection port of the color conversion member;-   (e) the step of curing the first and second encapsulation resin    materials to form the encapsulation member.

Also with this method, the encapsulation member can hardly suffer fromgeneration of the voids in the manufacturing process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a light emitting device inaccordance with a first embodiment.

FIG. 2 is an exploded perspective view of the above light emittingdevice with a portion broken away.

FIG. 3 is a plan view of an essential part of the above light emittingdevice.

FIG. 4 is a perspective view of a sub-mount member utilized in the abovelight emitting device.

FIG. 5A is a plan view of a dielectric substrate utilized in the abovelight emitting device.

FIG. 5B is a cross sectional view of the above dielectric substratetaken along line A-B-C-D in FIG. 5A.

FIG. 5C is a partly broken away bottom view of the above dielectricsubstrate of FIG. 5A.

FIG. 6 is an explanation view illustrating a method of manufacturing theabove light emitting device.

FIG. 7 is an explanation view illustrating a method of manufacturing theabove light emitting device.

FIG. 8 is a cross sectional view of a light emitting device inaccordance with a second embodiment.

FIG. 9 is an explanation view illustrating a method of manufacturing theabove light emitting device.

FIG. 10A is an explanation view illustrating a method of manufacturingthe above light emitting device.

FIG. 10B is an explanation view illustrating a method of manufacturingthe above light emitting device.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereafter, the invention will be explained in detail with reference tothe attached drawings.

FIRST EMBODIMENT

As shown in FIGS. 1 to 3, the light emitting device 1 of the presentembodiment includes an LED chip 10, a mounting substrate 20 to which theLED chip is mounted, a dome-shaped color conversion member 70, and anencapsulation member 50. The color conversion member 70 is molded from atransparent resin material, and a fluorescent material which is excitedby a light from LED chip 10 to emit a light of a color different from aluminescent color of the LED chip 10. The color conversion member 70 isfixed on the mounting substrate 20 to surround the LED chip 10 andindividual bonding wires 14 connected to the LED chip 10. Theencapsulation member 50 is made from an elastic encapsulation resinmaterial to encapsulate the LED chip 10 and the bonding wires 14 withinthe space confined between the mounting substrate 20 and the colorconversion member 70. The encapsulation member 50 is configured to havea convex lens shape with a light output surface 50 b which is held in anintimate contact with an interior surface of the color conversion member70.

The light emitting device 1 of the present embodiment is adapted in use,for example, as a light source of an illumination appliance, and ismounted to a metal body 100 of the appliance (e.g. the metal with a highthermal conductivity such as Al, Cu) through a dielectric layer 90 madeof, for example, a green sheet. As being mounted to the metal body 100of the appliance, a thermal resistance from the LED chip 10 to the metalbody 100 can be lowered to improve heat-dissipation capability. Further,since a temperature rise at a junction of the LED chip 10 can berestrained, an increased input power is available to give a high lightoutput. It is noted in this connection that, when the light emittingdevice 1 is used for the illumination appliance, a plurality of thelight emitting devices 1 may be mounted to the metal body 100 of theappliance in order to obtain an intended output light power with theemitting devices being connected in series or parallel with each other.

The mounting substrate 20 includes a metal plate (heat conductive plate)21 made of a thermal-conductive material and a dielectric substrate 22made of a glass epoxy (FR4) board and superimposed on the metal plate21. Although the metal plate 21 is made of Cu in the present embodiment,it may be made of another metal having a relatively high thermalconductivity such as Al. The metal plate 21 is secured to the dielectricsubstrate 22 by means of a conjugative metal layer 25 (see, FIG. 1 andFIG. 5B, FIG. 5C.) which is made of a metallic material (in thisembodiment, Cu) deposited on the surface of the dielectric substrate 22opposed to the metal plate 21.

The dielectric substrate 22 includes a pair of lead pattern 23 coupledelectrically to both electrodes (not shown) on a surface the LED chip 10opposed to the metal plate 21, and is formed with a through-opening 24at a position corresponding to the LED chip 10.

The LED chip 10 is mounted to the metal plate 21 through a planarsub-mount member 30 disposed within the through-opening 24. Thesub-mount member 30 is shaped into a rectangular plate which isdimensioned to be larger than the LED chip 10, and thermally couples theLED chip 10 to the metal plate 21 in order to relieve a stress appliedto the LED chip 10 due to a difference in linear expansion coefficientbetween the LED chip and the metal plate 21. A heat generated in the LEDchip 10 is transmitted to the metal plate 21 not through the dielectricsubstrate 22. The sub-mount member 30 has a thermal conductiveperformance so as to radiate the heat generated in the LED chip 10 tothe metal plate 21 over a wider area than the chip size of the LED chip10. Since the LED chip 10 is thus mounted to the metal plate 21 throughthe sub-mount member 30 in the present embodiment, the heat generated inthe LED chip 10 can be radiated efficiently through the sub-mount member30 and the metal plate 21, while it is made to relieve the stressapplied to the LED chip 10 due to the difference in linear expansioncoefficient between the LED chip 10 and the metal plate 21.

In the embodiment, although AlN is adopted as a material of thesub-mount member 30 because of its relatively high thermal conductivityand insulating performance, the material of the sub-mount member 30 isnot limited to AlN, and may be one (e.g. composite SiC, Si, or and thelike) having the linear thermal expansion coefficient relatively closeto that of an electrically-conductive substrate 11 made of 6H—SiC, andrelatively high thermal conductivity.

Further, the sub-mount member 30 includes a reflecting film (e.g.laminate of Ni film and Ag film) formed around the conductive pattern 31to reflect the light emitted from the LED chip 10.

Each lead pattern 23 is provided as a laminate of Cu film, Ni film, andAg film. A resist layer 26 (see FIG. 1 and FIG. 5A, FIG. 5B) made from awhitish resin is superimposed on a surface of the dielectric substrate22 away from the metal plate 21 to cover each lead pattern 23. Theresist layer 26 is formed in its center with a circular opening 26 a ata center in order to expose inner leads 23 a of each lead pattern 23,and at its corners respectively with circular openings 26 b in order toexpose outer leads 23 b of each lead pattern 23.

The LED chip 10 is a GaN-based blue LED chip emitting a blue light. TheLED chip 10 includes the electrically conductive substrate 11 made of anelectrically conductive n-type SiC having a lattice constant and acrystalline structure closer to those of GaN than sapphire. Formed onthe main surface of the electrically conductive substrate 11 is a lightemitting part 12 which is made of GaN-based semiconductor material andis obtained by an epitaxial growth (e.g. MOVPE process) to have alaminated structure, e.g. double-hetero structure. A cathode electrode(n-type electrode) (not shown) is formed on the rear side of theelectrically conductive substrate 11 as an electrode on the side of thecathode. An anode electrode (p-type electrode) (not shown) is formed onthe surface (a frontmost surface of the principle surface of theconductive substrate 11) of the light emitting part 12 as an electrodeon the side of the anode. In short, the LED chip has the anode electrodeon its one surface, and the cathode electrode on the other surface. Thesub-mount member 30 has the conductive pattern 31 on a surface facingthe LED chip 10 (as shown in FIG. 4). The LED chip 10 has the cathodeelectrode electrically contacted to one of the lead patterns 23 throughthe conductive pattern 31 and through the bonding wires 14 (e.g. goldthin wire, aluminum thin wire, and the like), and has the anodeelectrode electrically connected to the other lead pattern 23 throughthe bonding wires 14.

Although the cathode electrode and the anode electrode are each composedof the laminate of Ni film and Au film in the embodiment, materials ofthe cathode electrode and the anode electrodes are not particularlylimited, and may be one having a good ohmic property (e.g. Al and thelike). Further, the present embodiment illustrates that the LED chip 10is mounted to the metal plate 21 with the light emitting part 12 of theLED chip 10 being spaced further away from the metal plate 21 by way ofthe sub-mount member 30 than the electrically conductive substrate 11.However, it is equally possible to mount the LED chip 10 to the metalplate 21 with the light emitting part 12 being closer to the metal plate21 than the electrically conductive plate 11. Although it is desirableto space the light emitting part 12 away from the metal plate 21 from aviewpoint of optical extraction efficiency, the close disposition of thelight emitting part 12 to the metal plate 21 does not increase theoptical extraction loss because of that the electrically-conductivesubstrate 11 and the light emitting part 12 have the refractive index ofthe same level in the present embodiment.

It is noted in this connection that, although the LED chip 10 and thesub-mount member 30 can be joined by a solder such as SnPb, AuSn,SnAgCu, or a silver paste, they are preferably joined by use of a leadfree solder such as AuSn, SnAgCu.

The encapsulation member 50 includes the light output surface 50 bformed by one part of a spherical surface and is disposed to have acenter of the spherical surface aligned with a center line of the lightemitting part 12 extending through the LED chip 10 in a thicknessdirection thereof. In another words, the encapsulation member 50 isformed to have a lens of which optical axis is aligned with the centerline of the light emitting part 12 extending through the center of theLED chip 10 in a thickness direction thereof. In the embodiment, theencapsulation member 50 may be made of an acrylic resin instead of thesilicone resin.

The color conversion member 70 is molded from a mixture of thetransparent resin material, e.g. silicone resin and a particulateyellowish fluorescent material which is excited by the blue lightemitted from the LED chip 10 and passing through the encapsulationmember 50 to radiate a broad-band yellowish white light. The colorconversion member 70 is secured at its periphery to the mountingsubstrate 20 by an adhesive (e.g. silicone resin, epoxy resin), forexample. The light emitting device 1 of the present embodiment can giveoff the white light which is a combination of the blue light emittedfrom the LED chip 10 and the light emitted through the yellowishfluorescent material, and radiated through an outer surface 70 b of thecolor conversion member 70. The transparent resin material used for thecolor conversion member 70 is not limited to the silicone resin, but mayinclude a material which has a higher refractive index than one of anencapsulation resin material used for the encapsulation member 50 and alinear expansion coefficient closer to that of the encapsulation resinmaterial. When the acryl resin is used as the encapsulation resinmaterial of the encapsulation member 50, it may be also employed as thetransparent resin material of the color conversion member 70. Further,the fluorescent material mixed to the transparent resin material for thecolor conversion member 70 is not limited to the yellowish fluorescentmaterial, and may be replaced with a mixture of a reddish fluorescentmaterial and a greenish fluorescent material which gives a white light.

Preferably, the color conversion member 70 is configured to have itsinterior face 70 a held in an intimate contact with the light outputsurface of the encapsulation member 50 and shaped into a sphericalsurface centered on the LED chip 10. In this instance, the difference inoptical paths of the light emitting from the LED chip 10 towards variousportions of the color conversion member 70 can be lowered to therebyreduce color ununiformity. Further, the color conversion member 70 isformed to have uniform thickness along a normal line for eachcircumferential point.

In order to prevent a leakage of the light emitted from the lateral sideof the LED chip 10 through a juncture between the color conversionmember 70 and the mounting substrate 20 (i.e., prevent the blue lightfrom the LED chip 10 from radiating outwardly not through the colorconversion member 70), it is preferred that the surface of the LED chip10 facing the sub-mount member is spaced further away from the metalplate 21 than an edge of the color conversion member 70 adjacent to themounting substrate is spaced from the metal plate 21. For this purpose,the present embodiment is configured to select the thickness of thesub-mount member 30 such that the surface of the LED chip 10 adjacent tothe sub-mount member 30 is spaced further away from the metal plate 21than the edge of the color conversion member 70. In more detail, thethickness of sub-mount member 30 is adjusted such that the bottom of theLED chip 10 is spaced away from the uppermost surface (a surface of theresist layer 26) of the mounting substrate 20 in a direction normal tothe surface plane thereof.

Next, an explanation is made as to a method of manufacturing method thelight emitting device 1 in accordance with the present invention.

As shown in FIG. 6, the light emitting device could be manufactured byone method in which the LED chip 10 is firstly connected to the bondingwires 14, then the color conversion member 70 is filled in its insidewith an uncured encapsulation resin material 50 c (e.g. silicone resin)which forms the encapsulation member 50 later on, and subsequently theencapsulation resin material is cured to form the encapsulation member50 with the color conversion member 70 held in position on the mountingsubstrate 20. However, such method would suffer from generating voids inthe encapsulation member 50.

In view of this, the manufacturing method of the present embodiment ispreferred to include the following steps. Firstly, the LED chip 10 ismounted to the mounting substrate 20 to be connected thereto by means ofthe bonding wires 14 (step (a)). Secondly, as shown in FIG. 7, the LEDchip 10 and the bonding wires 14 are covered by an uncured firstencapsulation resin material (for example, silicone resin) 50 a whichbecomes one part of the encapsulation member 50 (step (b)). Next, anuncured second encapsulation resin material (for example, siliconeresin) 50 b, which is made of the same as the first encapsulation resinmaterial 50 a and becomes the other part of the encapsulation member 50,is injected into the color conversion member 70 followed by the colorconversion member 70 being positioned on the mounting substrate 20 (step(c)). After that, each of the encapsulation resin materials 50 a, 50 bare cured to form the encapsulation member 50 (step (d)). Thismanufacturing method can reduce a possibility of generating the voids inthe encapsulation member 50, and can provide the light emitting device 1with a high reliability and a large light output.

In the present embodiment, the circular-shaped opening 26 a formed in acenter part of the resist layer 26 on the mounting substrate 20 isconfigured to have an inner diameter which is slightly larger than amaximum outer diameter of the color conversion member 70, and a portionof the first encapsulation resin material 50 a flows into the interiorof the opening 26 a while being potted so as to be utilized as anadhesive for securing the color conversion member 70 to the mountingsubstrate 20.

As mentioned in the above, the light emitting device 1 of the presentembodiment in configured to make the convex lens-shaped encapsulationmember 50 in intimate contact with the interior face of the colorconversion member 70 without relying upon a conventional frame.Accordingly, the device is given improved reliability as a consequenceof eliminating generation of the voids in the encapsulation member in alow-temperature period of heat cycle test. Further, the device givesimproved light output as a consequence of requiring no conventionalframe. Moreover, the use of the small-sized color conversion member 70can reduce the amount of the fluorescent material and therefore enableit to make the device at a low cost. Further, the encapsulation member50 of the convex lens shape eliminates the use of an additional lens tothereby avoid the lowering of the light output due to the optical axismisalignment between the LED chip 10 and the lens, in addition toreducing the number of the components.

SECOND EMBODIMENT

The light emitting devices 1 of the present embodiment has a basicstructure similar to the first embodiment, and therefore like parts aredesignated by like reference numerals and dispensed with duplicateexplanations.

In this embodiment, as shown in FIG. 8, the color conversion member 70is formed with an injection port 71 for pouring an encapsulation resinmaterial into the space confined between the color conversion member 70and the mounting substrate 20, and also with a discharge port 72 fordischarging the excess of the encapsulation resin material.

Further, the color conversion member 70 is bonded at its edge to themounting substrate 20 by the juncture 75 made of an adhesive extendingalong the entire circumference of the edge. Thus, the light emittingdevice 1 of the present embodiment is easy to adjust the thickness ofthe juncture 75 between the color conversion member 70, and the mountingsubstrate 20 and is given improved reliability of bonding the colorconversion member 70 to the mounting substrate 20, in comparison withthe device of the first embodiment. In this instance, the adhesive ofthe juncture 75 is preferably the same material as the color conversionmember 70.

The light emitting device 1 of the present embodiment is preferred to bemanufactured with the following steps. Firstly, the LED chip 10 ismounted to the mounting substrate 20, and the LED chip 10 is connectedto the mounting substrate 20 by means of the bonding wires 14 (step(a)). Secondly, as shown in FIG. 9, the color conversion member 70 isadhered to the mounting substrate 20 at the juncture portion 75 (step(b)). Next, an uncured encapsulation resin material is filled within thespace confined between the color conversion member 70 and the mountingsubstrate 20 through the injection port 71 of the color conversionmember 70 (step (c)). After that, the encapsulation member 50 is formedby curing the encapsulation resin material (step (d)). With thismanufacturing method, voids are hard to be generated in theencapsulation member 50 during the manufacturing process.

Further, the manufacturing method of the light emitting device 1 ispreferred to include the following steps. Firstly, the LED chip 10 ismounted to the mounting substrate 20, and the LED chip 10 is connectedto the mounting substrate 20 by means of the bonding wires 14 (step(a)). Secondly, as shown in FIG. 10A, the LED chip 10 and the bondingwires 14 are covered by the uncured first encapsulation resin material(e.g. silicone resin) 50 a which becomes one part of the encapsulationmember 50 (step (b)). After that, the color conversion member 70 isadhered to the mounting substrate 20 (step (c)). Next, the uncuredsecond encapsulation resin material 50 b, which is the same as the firstencapsulation resin material 50 a and becomes the other part of theencapsulation member 50, is filled within the space confined between thecolor conversion member 70 and the mounting substrate 20 through theinjection port 71 of the color conversion member 70 (step (d)).Thereafter, the first encapsulation resin material 50 a and the secondencapsulation resin material are cured to form the encapsulation member50 (step (e)). This instance has therefore an advantageous in that theencapsulation member 50 is made more reluctant to generate the voids.

Although each of the above embodiments employs the blue-light LED chipwith the blue luminescence as the LED chip 10 and the SiC substrate asthe electrically conductive substrate 11, a GaN substrate may be usedinstead of the SiC substrate. The use of the SiC substrate and the GaNsubstrate as an epitaxial growth substrate enables to increase thermalconductivity and lower the heat resistance thereof, in comparison withthe use of a sapphire substrate as a dielectric epitaxial growthsubstrate. Further, the luminescent color of the LED chip 10 is notlimited to be blue, and may be red, green or the like. Namely, amaterial of light emitting part 12 of the LED chip 10 is not limited toa compound of GaN-based semiconductor material, and may be selected froma compound of GaAs-based, GaP-based semiconductor materials, or thelike, depending on the luminescent color of the LED chip 10. Besides,the electrically conductive substrate 11 is not limited to SiCsubstrate, and may be optionally selected from GaAs substrate, GaPsubstrate, and the like, depending on the material of light emissionportion 12. Furthermore, it should not be noted that the sub-mountmember 30 explained in each of the above embodiments is not necessarilyprovided in a circumstance where there is only a small difference of thelinear expansion coefficient between the LED chip 10 and the mountingsubstrate 20. Moreover, the mounting substrate 20 may be configureddifferently from that explained in the each of the above embodiments.

As discussed in the above, apparently many widely different embodimentsmay be made without departing from the technical concept of the presentinvention, and therefore the present invention should not be limited tothe specific embodiments except as defined in the claims.

1. A light emitting device comprising: an LED chip; a mounting substratemounting said LED chip; a dome-shaped color conversion member made of atransparent resin material and a fluorescent material which is excitedby a light emitted from said LED chip to emit a light of a colordifferent from a luminescent color of the LED chip, said dome-shapedcolor conversion member being bonded on the mounting substrate tosurround the LED chip; and an encapsulation member disposed in a spaceconfined between the mounting substrate and the color conversion memberto encapsulate the LED chip, said encapsulation member being made of anencapsulation resin material, wherein said encapsulation member has aconvex lens-shape such that a light output surface of the encapsulationmember is held in an intimate contact with an internal surface of thecolor conversion member.
 2. The light emitting device as set forth inclaim 1, wherein said mounting substrate includes a heat conductiveplate made of a heat conductive material and a dielectric substratestacked on said heat conductive plate, said dielectric substrate beingformed with a pair of lead patterns on its surface opposite to said heatconductive plate for electrical connection respectively with electrodesof said LED chip, wherein said dielectric substrate has athrough-opening at a portion corresponding to said LED chip, whereinsaid LED chip is mounted to said heat conductive plate inside of thethrough-opening with a planar sub-mount member interposed between saidLED chip and said heat conductive plate, and wherein said sub-mountmember is larger than the LED chip and is configured to thermally couplethe LED chip to the heat conductive plate so as to relieve a stressapplied to said LED chip due to a difference in linear thermal expansioncoefficient between said LED chip and said heat conductive plate.
 3. Thelight emitting device as set forth in claim 2, wherein said sub-mountmember has a thickness such that the surface of said LED chip facing thesub-mount member is spaced from said heat conductive plate by a distancegreater than that between the heat conductive plate and an edge of saidcolor conversion member adjacent to the mounting substrate.
 4. The lightemitting device as set forth in claim 1, wherein said color conversionmember is shaped to have said internal surface which is spherical aboutthe LED chip and in an intimate contact with the light output surface ofthe encapsulation member.
 5. The light emitting device as set forth inclaim 1, wherein said color conversion member has an injection port forinjecting said encapsulation resin material into the space confinedbetween the color conversion material and the mounting substrate and adischarge port for discharging an excess amount of said encapsulationresin material.
 6. A method of manufacturing the light emitting deviceas defined in claim 1, said method comprising the steps of: (a) mountingsaid LED chip to said mounting substrate, and connecting said LED chipto said mounting substrate by means of bonding wires; (b) covering saidLED chip and said bonding wires with an uncured first encapsulationresin material which becomes a part of said encapsulation member; (c)filling up inside of said color conversion member with an uncured secondencapsulation resin material which is the same material of said firstencapsulation resin material and becomes the other part of saidencapsulation member so as to position the color conversion member onthe mounting substrate; and (d) curing each of said first and seconduncured encapsulation resin materials to form said encapsulation member.7. A method of manufacturing the light emitting device as defined inclaim 5, said method comprising the steps of: (a) mounting said LED chipto said mounting substrate, and connecting said LED chip to saidmounting substrate by means of bonding wires; (b) boding said colorconversion member to said mounting substrate to which the LED chip ismounted; (c) filling up a space confined between said color conversionmember and said mounting substrate with an uncured encapsulation resinmaterial through said injection port of the color conversion member; and(d) curing said uncured encapsulation resin material to form saidencapsulation member.
 8. A method of manufacturing the light emittingdevice as defined in claim 5, said method comprising the steps of: (a)mounting said LED chip to said mounting substrate, and connecting saidLED chip to said mounting substrate by means of bonding wires; (b)covering said LED chip and said boding wires with an uncured firstencapsulation resin material which becomes a part of the encapsulationmember; (c) after the step of (b), bonding said color conversion memberto said mounting substrate; (d) filling up a space confined between saidcolor conversion member and said mounting substrate with an uncuredsecond encapsulation resin material, which is the same material of saidfirst encapsulation resin material and becomes the other part of theencapsulation member, through said injection port of the colorconversion member; and (e) curing each said first and second uncuredencapsulation resin materials to form said encapsulation member.